The summer course "Molecular Mycology: Current Approaches to Fungal Pathogenesis" has been offered at the Marine Biological Laboratory since 1997 with the purpose to make the area of Medical Mycology accessible to those whose training involved other organisms, and to provide molecular training for classical Medical Mycologists. There is a great need for effective training of researchers who can address the molecular aspects of fungi in an effort to prevent, diagnose and treat infections caused by the fungal pathogens in immunocompromised indviduals. Sixteen to eighteen students who are outstanding graduate and post-graduate students and experienced investigators are immersed for three weeks in an interview schedule of laboratory work and lectures. The aims are to provide the students with: an introduction to the biology and pathogenesis of medically-important fungi; laboratory training in manipulation of these fungi, especially the applications of molecular and classical genetics, and assays of virulence and host-pathogen interaction; and a broad perspective on experimental issues pertinent to these fungi, such as the definition and determination of virulence, the determination of host responses relevant to infection, and the identification of antifungal drug targets. The course provides an introduction to the biology and pathogenesis of medically important fungi, including Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus. Specific laboratory exercises include biolistic transformation and manipulation of the Cryptococcus genome, tetrad dissection and meiotic analysis in fungal pathogens having sexual cycles, the use of gene disruption in analyses of gene function, gene cloning strategies, in vivo pathogenicity assays, and the identification of antifungal drug targets. During a relatively short period of time, this course has established a strong reputation in the field. Both the applicant pool and the faculty are of the highest quality. Funding is requested to continue this unique training opportunity in its present form.